1. Field
Embodiments described generally relate to methods for making paperboard blanks and paperboard products therefrom.
2. Description of the Related Art
Paperboard is used to make a wide variety of paperboard products, such as plates, bowls, and cups. Paper products can be insulated in a variety of ways to provide an insulated product, such as an insulated cup for hot or cold beverages. For example, the paper product can be insulated by forming an air gap within a sidewall of the product. The air gap, for example, can be located between a film that forms an inner surface of the sidewall and a paperboard substrate that forms an outer surface of the sidewall. The film can be a shrinkable film that can shrink, e.g., a heat shrinkable film, to form the gap between the film and the paperboard substrate as the film shrinks. As the shrinkable film shrinks and the gap forms, air or other fluid needs to flow into the gap.
One problem encountered in making an insulated product, such as a cup, with a shrinkable film is that the air required to fill the gap needs an adequate path to flow into the gap as the gap forms. Without an adequate flow path for the air to flow between the shrinkable layer and the paperboard substrate, a vacuum can form between the shrinkable film and the paperboard substrate that prevents or reduces the amount the shrinkable film can shrink. Preventing or reducing the amount the film shrinks can decrease the insulating properties of the product.
The conventional technique used to form a flow path for air to flow into the gap as the gap forms is to punch or cut a hole, slot, or other opening into the paperboard substrate with a pin, die, punch, or other physical tool. These punched openings, however, may not produce openings through the paperboard substrate that provide a flow path capable of consistently permitting a sufficient amount of air to flow through the paperboard substrate as the shrinkable film shrinks.
There is a need, therefore, for improved methods for making paperboard blanks having an adequate path for air to flow into the gap as the shrinkable film shrinks.